diff --git a/build/toolbase/gotoolchain/toolchain_test.go b/build/toolbase/gotoolchain/toolchain_test.go
index 7b93d6d..2f13d80 100644
--- a/build/toolbase/gotoolchain/toolchain_test.go
+++ b/build/toolbase/gotoolchain/toolchain_test.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 package gotoolchain
 
 import (